Question

Possible Duplicate:
MainWindow constructor getting called twice

I am developing a WPF application following the MVVM pattern as per the below link.
http://msdn.microsoft.com/en-us/magazine/dd419663.aspx

I copied some files from the sample (i.e. viewmodel base, Relaycommang etc) The application is working fine except at startup it displays two instance of Mainwindow.xaml.

I tried a lot to resolve but couldn’t trace out.

 public partial class App : Application
{
    static App()
    {
        // This code is used to test the app when using other cultures.
        //
        //System.Threading.Thread.CurrentThread.CurrentCulture =
        //    System.Threading.Thread.CurrentThread.CurrentUICulture =
        //        new System.Globalization.CultureInfo("it-IT");


        // Ensure the current culture passed into bindings is the OS culture.
        // By default, WPF uses en-US as the culture, regardless of the system settings.
        //
        FrameworkElement.LanguageProperty.OverrideMetadata(
          typeof(FrameworkElement),
          new FrameworkPropertyMetadata(XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));
    }

    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);

        MainWindow window = new MainWindow();

        // Create the ViewModel to which 
        // the main window binds.
        string path = "Data/customers.xml";
        var viewModel = new MainWindowViewModel(path);

        // When the ViewModel asks to be closed, 
        // close the window.
        EventHandler handler = null;
        handler = delegate
        {
            viewModel.RequestClose -= handler;
            window.Close();
        };
        viewModel.RequestClose += handler;

        // Allow all controls in the window to 
        // bind to the ViewModel by setting the 
        // DataContext, which propagates down 
        // the element tree.
        window.DataContext = viewModel;

        window.Show();
    }

}

Answer 1

Check your App.xaml file. Your view could be instantiated there as well as in code. Otherwise its hard to tell what the problem is whithout more information.